i use a 21 as my 'go to' because it translates to about a 32mm fov in 35mm terms. i find that i get great DOF for street shooting, storytelling or landscape. coupled with your 50mm, which is a nice 75mm portrait fov on the rd1, thats a nice kit right there. a 35mm lens will translate to a 50, so to me, theres not so much of a difference with your adjusted '75mm' industar, plus youre not getting a wide angle. just my 2¢.